Utilization of promoters in effecting reactions



April 23, 1963 E. N. HALL UTILIZATION OF PROMOTERS IN EFFECTINGREACTIONS Filed Oct. 2, 1958 FUEL F) 00/ 7/ v5 comm/snow TFINK CON 7E09/? 7/8/0615 CHHMBER Imam EDWARD A/ HALL ilnited rates 3,686,354UTILIZATION OF PROMOTERS KN EFFECTING REACTEONS Edward N. Hall, PalosVerdes, Calif, assignor to Avir Research Corporation, Los Angeles,Calif., a corporation of Delaware Filed Oct. 2, 1953, Ser. No. 765,004 9(Ilaims. {(Il. fill-35.4) (Granted under Title 35, 0.5. Code (1952),see. 266) The invention described herein may be manufactured and used byor for the United States Government for governmental purposes withoutpayment to .me of any royalty thereon.

This application is a cont-inuation-in-part of my copending applicationSerial No. 460,787, entitled Method of Utilizing Solid Fuel Additivesand Device Therefor which was filed on October 6, 1954, now abandoned.

This invention relates generally to the improved introduction of apromoter into a reaction region in a carrier which comprises one of thereactants to thereby more effectively carry out the reaction. Moreparticularly, the invention relates to a method and means for releasinghighly reactive promoters from an inert material and into a fluid streamcomprising a reactant, the mixture being then introduced into a reactionregion. The invention is especially important in jet and rocketpropulsion fuel systems wherein it is desirable to add one or moresubstances to the fuel or oxidant component to thereby improve itsignition, combustion or other functional features.

In eifecting various reactions, .it is often desirable to promotecontrolled reaction as by stabilizing, triggering, or catalyzing thereaction. As is well known, this can be done by adding various agents,such as catalysts, stabilizers or triggering agents to the reactants inthe reaction region. For purposes of this application, such catalysts,stabilizers, trigger-im agents and agents which promote or moreeffectively carry out a reaction are referred to as promoters. Thepromoters are usually highly reactive, are often difiicult to handle,and are not readily added to the reactants.

By way of example, various types of propulsion systems, including pulseengines, turbo-engines and ram jet engines, and rockets, andparticularly those devices or engines using hydrocarbon fuels, aresubject to fuel combustion deficiencies under certain conditions ofoperation. One very important problem in connection with such propulsionsystems concerns the combustion instability which gives rise to cyclingwherein the flame front in the combustion chamber tends to fluctuateback and forth causing marked reduction in operating efliciency. Thiscombustion instability, under certain conditions, such as rich fuelmixtures or a high angle of attack of a plane or rocket, may cause theflame in the combustion chamber to become extinguished. It will bereadily apparent that this is a highly dangerous condition under certainoperating conditions.

Another problem of importance occurs in connection with hydrocarbonfuel-acid oxidant system because of ignition delay and hazardousstarting of the engines. This results from difiiculty in igniting thesystem which inherently causes an excessive buildup of the reactionelements prior to ignition of the mixture, thereby creating asubstantial safety hazard.

These problems have caused considerable research to bring about theirsolution and, in this connection, much has "been done to improvemechanical design to overcome the combustion instability and ignitionproblems so as to minimize delay in starting. Another research approachhas concerned the evaluation of many types of fuels having differingproperties in respect of ignition characteris- BfldhfiSi Patented Apr.23, 1963 ice tics, flame speeds, heats of combustion, smoke formation,and the like. In connection with this approach, fuel additives ofvarious types have been proposed and additives in the form of solids orfluids have been incorporated directly with the fuel in the supply tankof the unit.

In some cases, however, the additives may be incompatible with the fuelto such an extent that premixing of the fuel and additive is neitherdesirable nor possible. In such case, the additive must be added to thefuel while it is being transmitted or after it has reached thecombustion chamber, but usually prior to combustion of the fuel. Undercertain conditions, the additives may be readily metered into the fuelsystem at any desired point in the system by injection or other means ofintroduction. However, when the desired additive is in a solid phase andone which in insoluble or otherwise incompatible with the fuel and ishighly reactive, the problem of introducing the desired amount ofadditive at the proper time and place in the fuel system causes a greatdeal of difficulty which has not been satisfactorily solved inconnection with engines and rockets of the type herein discussed.

One approach to the problem of handling such additives is to form aslurry or suspension thereof in an approriate solvent so that the slurrymay be injected in such form in the desired amounts. This approach hasnot proven to be entirely satisfactory because the activity of thesuspended additive in liquid media often decreases rapidly so that thecombustion stabilization or other properties initially possessed by theadditive is not maintained.

While various problems have been detailed in the foregoing in respect ofthe combustion of fuels in various types of engines and rockets, it willbe apparent to those familiar in the art that similar problems can occurwith diesel engines, gas turbines and gas generators.

Likewise, similar problems occur in respect of other reactions thanoixdation or combustion reactions which involve the addition ofpromoters for more effectively carrying out the reaction. In thisconnection, many catalytically effected reactions will be apparent tothose familiar with the art.

A main object of this invention is the provision of an improved methodand means for introducing a promoter into a reaction. It is amorevparticular object of this invention to provide an improved methodand means for introducing a promoter into a carrier which comprises areactant in a reaction region. A still more particular object of theinvention is the provision of a method and means for introducing ahighly reactive fuel additive in particulate form and in particularamounts into a stream of fuel prior to ignition and combustion. Afurther object of this invention is the provision of an additivedispensing cartridge which, when placed in a stream, results in thetransfer of the additive from the cartridge to the stream. It is a stillfurther object of this inven tion to provide a fuel additive dispensingcartridge which is adapted to liberate substantially uniform amounts ofadditive into fuel flowing through the cartridge. Other objects andadvantages of this invention will become apparent by reference to theaccompaning drawing and the following specification.

In accordance with this invention a promoter is carried into a reactionregion in a carrier. In carrying out the invention, the promoter issurrounded by a material which is inert relative to the promoter but isreactive with the carrier so that when the carrier is passed over theinert material some of the promoter becomes suspended in the carrier andthe carrier reacts with the inert material to activate the promoter forreaction. The carrier is a fluid and is preferably a reactant in thereaction region. The carrier is selected so as to react with the inertmaterial by effecting dissolution, sublimation, disintegration, ordecomposition of the inert material at a controlled rate to therebyrelease the promoter from the inert material into the carrier.

The promoter may be dispersed in the inert material or matrix in theform of a solid or in the form of a liquid. In the event that a liquidis employed, the liquid is desirably capsulated and the capsules aredispersed in the solid material. If the promoter is capsulated, it willbe understood that the capsule material should be reactive With thecarrier and inert to this promoter so that the carrier can release thepromoter from the capsules. Of course, if the promoter is in solid form,the solids are finely ground for dispersion throughout the solidmaterial.

The inert material may either be liquid or solid so long as it is inertrelative to the promoter and reactive with the carrier to release thepromoter from the inert material'for reaction inthe reaction region.

The promoter, as before indicated, may serve to effect more improvedreactions in various Ways but, in the case of various engines androckets, the promoters are highly reactive chemical materials havingvery low ignition energy requirements, such as various known pyroforicand auto igniting substances. These substances include alkali metals,chelates of many metals, organic metallic compounds. phosphorous, andothers.

These promoters, in accordance with this invention, are dispersed in aninert, solid substance in the form of a device so that the entire deviceis inert and storable until used. As previously indicated, the inertsolid substance is inert relative to the promoter but, at the same time,should be selected so that the carrier releases the promoter therefromat a desired rate for reaction. It will be apparent that the selectionof the solid material will be a function of the type of carrier which isemployed for the promoter. For example, if the carrier is an acid, thepromoter may be dispersed in a metallic substance. On the other hand, ifthe carrier is a hydrocarbon, the solid material may be a solidhydrocarbon, such as wax which will dissolve at a controlled rate insaid carrier. In this connection, the carrier will usually comprise arelatively short chain hydrocarbon, as compared to the hydrocarbon fromwhich the inert material is formed.

In summary, in accordance with this invention, the inert material inwhich the promoter is disposed may either be solid or liquid but it mustbe reactive with the carrier to release the promoter to the carrier. Ifa solid inert material is utilized, the promoter disposed therein mayeither be in the solid form or in a liquid form. The solid form ofpromoter may be either capsulated or merely dispersed. When a liquidpromoter is used, it should be capsulated for dispersion in the inertmaterial.

If a liquid inert material is employed, the solid promoter may also becapsulated or merely dispersed in the liquid inert material. Of course,if a liquid promoter is utilized in a liquid material, the promoter willbe capsulated.

By way of a particular example of this invention, a fuel additive(promoter) substances including alkali metals such as sodium and thelike may be readily transferred to the fuel stream (carrier) of anengine in the required concentrations without encountering thedifliculties previously mentioned. This is made possible by forming anadditive stick or cartridge device utilizing the additive as a dispersedphase in an apertured matrix (inert material) formed from a bodyingagent having predetermined solubility characteristics in the fuel. Bypositioning the additive-containing cartridge within the fuel systemupstream of the combustion zone, the flow of the fuel through theapertured core disintegrates or reacts with the aperture-forming surfaceof the matrix at a rate sufficient to release the prerequisite amount ofadditive for pickup and utilization by the fuel.

It is thus seen that the incorporation of a fuel additive into the fuelin accordance with the method of this invention is independent ofmetering or injection devices feeding the additive from an externalsource. By contrast, an excess of the additive is inserted directly intothe fuel stream and the availability of the additive to the fuel isregulated by the eroding or solubilizing action of the fuel itself onthe solid core. Where extremely small amounts of the additive aresufficient to produce the desired ignition or combustion modification,the solubility of the bodying agent constituting the solid matrix of thecartridge need be only minimal. Where relatively higher concentrationsof the additive are required, the solubility of the matrix material maybe varied accordingly. Similarly, the concentration of the additive inthe solid core can be varied to provide for the release ofproportionately differing amounts of additive as required. Since theamount of releasable additive is also dependent upon the total surfaceof the cartridge exposed to the solubilizing or eroding action of thefuel in contact therewith, the geometry of the cartridge surfacesexposed to the fuel flow becomes of importance in minimizing changes intotal area.

It is known that alkali metals such as sodium, potassium, etc. andalloys thereof exert a beneficial effect particularly when used inconjunction with hydrocarbon fuels and acid oxidants. For example, theautoignit-ing effect, i.e. the ignition reaction acceleration producedby the addition of sodium and other substances into hydrocarbon fuelsdesignated as JP-3 and ZIP-4 which are subsequently oxidized with red orwhite fuming nitric acid oxidants has been clearly established. Otherfuel additive substances capable of forming a dispersed phase in solidmatrices can be used in accordance with the present invention andillustrative substances in addition to sodium and potassium includelithium, calcium, and alloys of sodium and potassium and the like.Alkali metal salts of organic acids such as abietic, olaic, stearic,etc. may also be used and metal complexes with compounds such asanthracene, naphthalene, and the like wherein the metal is loosely heldin the molecule can also be utilized. The particle size of the additivematerial should be maintained at a minium in order to maintain themaximum inherent reactivity thereof and also to provide for improveddistribution upon its release into the fuel stream. Preferably, theaverage particle size should be below 50 microns and agglomerationbetween the particles during processing of the mixture to form thedispersed phase in the solid matrix should be avoided as much aspossible. As before indicated, the additive may be in liquid form andcapsulated for dispersion in the matrix.

The bodying agents suitable for use as dispersing media for the fueladditive consists of various substances including rubber, Wax, plasticor resin compositions which desirably have the following properties andcharacteristics: (1) impermeability to air and moisture, (2) reactivewith the carrier to release the additive and compatible with thepromoter such that the effectiveness of the active ingredient isunimpaired, (3) conducive to shaping into any desired configuration asby casting, molding, etc. and (4) adequate mechanical strength toprovide structural integrity under actual conditions of engine operationand storage over the ranges of temperature, acceleration, shockcondition and other factors to which the device made therefrom issubjected throughout its life.

Examples of specific materials useful as bodying agents ly in section,of a preferred embodiment of the fuel additive device of this invention.FIGURE 2 is a similar view of a modified form of the device. FIGURE 3 isa sectional view illustrating the use of one embodiment of the devicewithin a portion of the fuel system and FIGURE 4 is a diagrammaticdrawing of a fuel system incorporating the present invention.

With reference to FIGURES 1 and 2, the bodying agent, prefeerablyconsisting of a high melting paraffin wax (M.P. above 120 F.), is formedinto any desired shape illustrated by the cylindrical solid coredesignated as matrix provided with an internal aperture throughout itslength to permit fuel flow therethrough. The aperture-forming surface ispreferably designed to provide for minimum change of total surface asthe same becomes gradually eroded by fuel flow and this can beconveniently achieved by a symmetrical arrangement of webs 11 and ports12 arranged transversely or longitudinally forming the undulatedsurfaces shown in FIG- URES 1 and 2 respectively. The fuel additivecomponent 13 consisting of finely divided particles is shown as adispersed phase in matrix 10 including the apertureforming surfacesdefined by webs 11 and ports 12 and, in its entirety, the unit isreferred to as a reaction promoter dispensing cartridge.

The utilization of the fuel additive dispensing cartridge within thefuel system is illustrated in FIGURE 3 wherein the cartridge is showninserted in the fuel line 14. The flow of fuel 15 through the apertureformed by webs 11 and ports 12 during operation of the engine results ina pickup of the additive 13, the quantity being dependent upon thesolubility of the solid core, rate of fuel flow, total surface exposedto fuel flow, and the concentration of additive in the matrix. Thepositioning of the cartridge within the fuel system as indicateddiagrammatically in FIGURE 4 is between the fuel tank and combustionZone and preferably as shortly upstream of the combustion zone aspossible prior to mixing of the fuel with the oxidant to minimizedeterioration of the additive once it is released from its source.

The amount of additive in the cartridge can be varied broadly as neededfor a given application. For example, in the case of theautoigniteability manifested by sodium in the hydrocarbon-fuming nitricacid systems previously mentioned, less than 0.1 percent by weight ofsodium in the fuel is sufficient to produce the stated effect. Thepre-requisite amount can be made available to the fuel from thecartridge by variation or adjustment of either or all of variablespreviously mentioned including (1) solubility of the matrix under thefuel flow conditions involved at the temperature of engine operation,(2) surface area available for dissolution and simultaneous release ofthe additive substances and (3) the concentration of the additive in thematrix. Hence it is seen that the solubility of the substrate materialcomprising the matrix need not be varied in each and every case wheredifferent amounts of the active ingredient are required by the fuel.Ordinarily, upwards of 50 percent by weight of particulate additivesubstance such as sodium can be mechanically dispersed in wax, rubber,resin or plastic matrix materials utilizing well known techniquesincluding the use of emulsifiers to prevent agglomeration of theparticles during the processing of the mixtures.

After a suitable vehicle has been selected as the matrix material, theinitial phase of fabricating the solid core may be carried out byvarious procedures involving the use of different types of mixingapparatus such as a colloid mill, ultrasonic mixer, Waring Blendor, andthe like, whereby micron size disintegration of the particulate additivecan be satisfactorily achieved in the molten matrix medium. In general,the matrix material and the additive are melted together and processedin an inert atmosphere to form the dispersion. If desired, the additivemay be previously disintegrated in a suitable solvent such as toluene,in the case of sodium, and the dispersion is then added to the moltenmatrix material with high speed agitation while maintaining the systemunder an inert gas. Emulsifying agents consisting of metal salts offatty acids may be used in concentrations of from .05 to .5 percent byweight to minimize agglomeration or otherwise improve its dispersion.

The molten dispersion maintained in an inert atmosphere is then pouredinto a suitably shaped mold adapted to provide the desired internal andexternal configuration of the cartridge. Either casting or moldingprocedures can be used and preferably a combination of both methods areutilized wherein the molten mass is cast and then compressed in ahydraulic press at between 2000- 8000 psi. The dispersion may be formedin long strips if desired and cut to the desired length as required.

While in the foregoing, the invention has been particularly described inrespect of introducing an additive into a fuel from a solid matrix, itwill be readily apparent that other promoters, such as a nickelcatalyst, may be introduced into other carriers, such as liquid edibleoil, by dispersion of the catalyst in other inert materials, such ashard edible fats, to introduce the promoter into the liquid material fora reaction, such as hydrogenation.

It is not believed necessary to detail each of the possible combinationsfor purposes of this invention but one understanding the teachings ofthe invention will be readily able to employ the invention for promotinga substantial number of reactions.

I claim:

1. In a propulsion system, an operating method which comprises the stepsof dispersing a combustion-modifying additive in a material which ischemically inert to said additive, but which is reactable withcombustible fluid to release said additive, contacting combustible fluidwith said inert material to thereby release at least a portion of saidadditive from said inert material and disperse said additive in saidcombustible fluid, and thereafter passing said additive bearingcombustible fluid to a combustion zone for combustion of said fluid.

2. In a propulsion system, an operating method which comprises the stepsof dispersing a fuel combustion-modi fying additive in a material whichis chemically inert to said additive but which is soluble in fluid fuel,contacting fluid fuel with said material so as to dissolve at least aportion of said material and uniformly disperse said additive in saidfuel, passing said additive-bearing fuel to a combustion zone andtherein spark igniting said fuel.

3. In a propulsion system, an operating method which comprises the stepsof uniformly dispersing a fuel-modifying additive in a solid materialwhich is chemically inert to said additive but which reacts with fluidfuel to uniformly disperse said additive in said fuel, passing fluidfuel from a fuel supply to a combustion zone and en route reacting saidfuel with said solid material, whereby said additive is uniformlydispersed in said fuel, and thereafter spark igniting saidadditive-bearing fluid fuel in said combustion zone.

4. In a propulsion system, an operating method which comprises the stepsof dispersing a fuel combustion-modifying additive in a solidhydrocarbon material which is chemically inert to said additive butwhich is soluble in liquid hydrocarbon fuel, passing liquid hydrocarbonfuel from a fuel supply to a combustion zone and en route contactingsaid fuel with said solid hydrocarbon material, whereby at least aportion of said solid hydrocarbon material is dissolved, therebyuniformly dispersing said additive in said fuel, and thereafterspark-igniting the additivebearing fuel in said combustion zone.

5. The method of claim 4 wherein the fuel combustionmodifying additivecomprises alkali metal.

6. The method of claim 4 wherein the fuel combustionmodifying additivecomprises an alloy of potassium and sodium.

7. In a propulsion system, an operating method which comprises the stepsof inserting an ignition-improving, solid fuel additive-containingapertured cartridge in the path of fluid hydrocarbon fuel flow at alocation upstream of a combustion zone within a spark ignition-actuatedcombustion system, said cartridge including the ignition-improving solidfuel additive dispersed in a solid matrix soluble in hydrocarbon fuel,flowing fluid hydrocarbon fuel through said apertured cartridge toprogressively disintegrate said matrix, thereby releasing said additiveinto said fuel, and thereafter spark-igniting the additive-bearing fuelin a combustion zone.

8. The method of claim 2 wherein the solid fuel additive comprisesalkali metal.

9. The method of claim 2 wherein the solid fuel additive comprises analloy of potassium and sodium.

References Cited-in the file of this patent UNITED STATES PATENTS LymanJune 30, 1885 Newton Oct. 7, 1913 Viles June 12, 1951 Malina et a1. Oct.30, 1951 Hansley et a1 Dec. 18, 1951 Hansley et al. v Apr. 14, 1953 CarrOct. 20, 1953 Jones et a1. Aug. 3, 1954 Bevans Oct. 18, 1955

1. IN A PROPULSION SYSTEM, AN OPERATING METHOD WHICH COMPRISES THE STEPSOF DISPERSING A COMBUSTION-MODIFYING ADDITIVE IN A MATERIAL WHICH ISCHEMICALLY INERT TO SAID ADDITIVE, BUT WHICH IS REACTABLE WITHCOMBUSTIBLE FLUID WITH TO RELEASE SAID ADDITIVE, CONTACTING COMBUSTIBLEFLUID WITH SAID INERT MATERIAL TO THEREBY RELEASE AT LEAST A PORTION OFSAID ADDITIVE FROM SAID INERT MATERIAL AND DISPERSE SAID ADDITIVE INSAID COMBUSTIBLE FLUID, AND THEREAFTER PASSING SAID ADDITIVE BEARINGCOMBUSTIBLE FLUID TO A COMBUSTION ZONE FOR COMBUSTION OF SAID FLUID.